Some silanes and more particularly monosilane or silicon tetrahydride (SiH4) are used as silicon vector in techniques for the deposition of amorphous silicon, of polycrystalline silicon, of nanocrystalline or microcrystalline silicon, also known as nano- or micro-morphous silicon, of silica, of silicon nitride or of another silicon compound, for example in vapor phase deposition techniques.
Depositions as a thin layer of amorphous silicon and monocrystalline silicon obtained from silane make it possible to manufacture solar cells.
It is also possible to obtain coatings resistant to corrosion by acids, by cracking of silane and manufacture of compounds such as silicon carbide.
Finally, the silane is capable of adding to single or multiple bonds of unsaturated hydrocarbons to give organosilanes.
The monosilane market will experience very strong expansion simultaneously in the manufacture of integrated semiconductors and the manufacture of thin-layer or crystalline solar (photovoltaic) cells, semiconductor components and the manufacture of flat screens.
Several types of processes described below have been used to date.
First of all, the reduction of SiCl4 by LiH in a KCl/LiCl bath at temperatures between 450° C. and 550° C. is known. The reaction yield is advantageous but the process is based, on the one hand, on the availability of LiH, whereas lithium resources are very limited, and, on the other hand, on the possibility of recycling the lithium metal by electrolysis. The reaction medium is highly corrosive and employs specific materials. This process has been used to produce small amounts of silane.
The reduction of SiF4 by NAlH4 in organic solvents medium is another example. This process is only viable industrially when there exists SiF4, the byproduct of another chemical production, and sodium to manufacture the sodium aluminum hydride. This process cannot be easily used, in particular for these two reasons.
Another known reaction is the acid attack in a liquid NH3 medium on a stoichiometric SiMg2 alloy. The reaction balance is as follows:

This process is carried out at a temperature close to ambient temperature at atmospheric pressure. This process is not satisfactory because of the difficulty of controlling the process and the use of liquid ammonia, which is subject to strict regulatory control.
Another known reaction is the dismutation of SiHCl3 over boronate resins or other resins. The complete process is thus described:    a) 4SiMetal+12HCl→4SiHCl3+4H2 (temperature between approximately 800° C. and approximately 1100° C.)    b) 4SiHCl3←→SiH4+3SiCl4 (ambient temperature)            3SiCl4+3H2→3SiHCl3+3HCl (temperature of approximately 1000° C.),        
i.e. the following reaction balance:4SiMetal+9HCl→SiH4+3SiHCl3+H2 
An alternative form of the above reaction is thus described:    a) 4SiMetal+16HCl→4SiCl4+8H2 (temperature of between approximately 1000° C. and approximately 1100° C.)    b) 4SiCl4+4H2→4SiHCl3+4HCl (temperature of approximately 1000° C.)    4SiHCl3→SiH4+3SiCl4,
i.e. the following reaction balance:4SiMetal+12HCl→SiH4+3SiCl4+4H2.
This process requires high temperatures in an extremely corrosive medium and consumes a great deal of energy (approximately 50 kWh/kg for stage b)). In order to achieve the maximum yield, stage b) requires numerous loops for recirculations of mixtures of chlorosilanes. Apart from the use of extremely corrosive, toxic and inflammable products, processes of such a type are very expensive in energy.
The generation of monosilane and higher silanes has been described in the Gmelin Handbook of Inorganic Chemistry, Si-Silicon, by reacting, in the aqueous phase, silicides and silicon alloys in an acidic or basic medium.
In patent applications EP 1 46 456 and WO2006/041272, a description is given of the synthesis of monosilane in the aqueous phase by dropping an AlxSiyCaz powder, x, y and z representing the respective percentages of aluminum, silicon and calcium, into an HCl solution. The composition of the gases produced was approximately 80% monosilane, 10% disilane and 5% trisilane, along with traces of disiloxane. This type of process exhibits the disadvantage of the handling and storage of pure or highly concentrated HCl. Byproducts resulting from such a reaction are produced in a large amount and are harmful to the environment. Another disadvantage of such a process is the copious formation of a foam in the reaction medium, which reduces the reaction yield and requires the presence of an antifoaming agent. Such a reaction is highly exothermic and temperatures of greater than 100° C. are fairly quickly achieved if the rate of introduction of the alloy powder is not greatly reduced.
None of these studies described above guarantees the conditions necessary for the achievement of a profitable process for industrial development.